i dont think it is jumping per say that makes ppl want to pull other their hair, its the abuse of it and the stupid things it can help u do.

Free jumping (so just pushing a button to jump) lets players hop around the map like rabbits, which just looks stupid and makes the game unrealistic (yes i kno, its a fantasy game w 2 foot midgets and dragons blah blah unrealistic) but come on, do u see a lot of ppl hopping up and down the streets?
Jump from really high places and dying/surviving. Again, it just makes the game look stupid. Having players jump from 100 story towers or into fires just kills realism from the game. As well as it makes the developers have to make every environment in the game movable by the player. Graphics and texture making in computer programs are linear (i.e. if i make the texture/graphics twice as good, it takes twice the memory/power to play) it is actually on scales of magnitude. So to make the game twice as good in terms of graphics, it actually takes 10x more work/memory/power to play. (numbers r made up, but the principle is sound) Can you imagine how hard it would be for the designers to make everything in the world in FFXIV walk about or swimable or whatever. It would be a lot of work